In recent years, many image processing apparatuses such as a printer, a scanner, a facsimile machine, or an apparatus with functions of these devices have a network communication function. Some of these image processing apparatuses have a network server function, as an information providing function of transmitting data, where setup window for setting the image processing apparatus is described, to a web browser on a PC, a server or the like connected to the apparatuses via a network, for user's setting and operations of device via the web browser. Further, some image processing apparatuses have a data transfer function of transferring image data or the like to a PC, a server or the like connected to the apparatuses via a network.
In the data transfer function, higher-order protocols such as the SMTP protocol for transfer of electronic mail, the i-Fax, the HTTP (Hyper Text Transfer Protocol) enabling file uploading and the FTP (File Transfer Protocol) for file transfer are used.
On the other hand, an external controller is known as a means of expanding the functions of the image processing apparatus. The external controller performs a network-function expansion function of converting data in the communication format of a user environment network (LAN) to data corresponding to the I/F format of the image processing apparatus, a storage expansion function of spooling communication data, a load distribution function of performing a part of processing by the image processing apparatus or a client apparatus, and the like.
Further, as the connection among the image processing apparatus, the external controller and the LAN, the dual network type connection where the external controller is connected between the image processing apparatus and the LAN and the external controller performs its interface function therebetween, and a single network type connection where the image processing apparatus and the external controller are respectively connected to the LAN are known.
In comparison with the single network type connection, the dual network type connection is advantageous in that the band of the LAN is not consumed since an independent local network is constructed between the external controller and the image processing apparatus. In the dual network type connection, a large amount of image data can be transmitted between the external controller and the image processing apparatus by using a transmission format of band wider than the LAN band the local network.
Further, in the dual network type connection, the external controller and the image processing apparatus operate as one network apparatus. On the other hand, in the single network type connection, the external controller and the image processing apparatus respectively consume logical resources such as network addresses and physical resources such as hub ports. Accordingly, the dual network type connection is advantageous in that the amount of consumption of network resources in the LAN is smaller than that in the single network type connection.
However, if the conventional external controller is connected between the LAN and the image processing apparatus, the image processing apparatus itself cannot perform communication on the LAN, and the above-described data transfer function of the image processing apparatus cannot be utilized on the LAN.